Computers such as servers and the like are enclosed within an electronics rack or enclosure that provides multiple functions such as protecting operating components from damage and shielding against undesirable electromagnetic emissions. With the advent of computer rooms and data centers, and the more recent trend toward collocation facilities, such electronics enclosures are often configured to be mounted in a standard-size cabinet commonly referred to as a system rack, enclosure or cabinet. Such a cabinet, referred to herein as a system rack or, more simply, a rack, can house multiple collocation computers and other systems such as fan assemblies and wiring patch bays. These and other devices and systems which are configured to be mounted in a system rack are generally and collectively referred to herein as rack-mount modules.
Rack-mount modules are commonly installed in system racks by directly or indirectly fastening the modules to the rack. Such arrangements sometimes utilize a bracket or tray also fastened to the rack to provide additional support for the installed module. When installed in this way the module remains in a stationary position relative to the rack while the module is in operation. Access to such a module requires the module to be taken off-line, unfastened and physically separated from the rack, and placed on a floor, bench, table or other supporting surface. Such a mounting approach is suitable for many rack-mount modules.
However, the current trend has been to provide rack-mount modules that require periodic and/or rapid access. For example, certain modules such as servers contain hot-plug components (e.g., PCI cards) that can be replaced online. Such modules are typically mounted on a carrier rail system in the system rack so that the module can be serviced without interrupting real-time operations. FIGS. 1A-1C are three schematic side-views of a system rack 100 with a rack-mount module 102 mounted on a conventional carrier rail system 104. Carrier rail systems (also commonly referred to as slide rails and guide rails) provide mechanical support for module 102 along a continuum of positions relative to system rack 100, including a number of interior 108 and adjacent exterior positions 110. Traditionally, a carrier rail system includes two linear slides interposed between module 102 and system rack 100 on opposing sides of the module. (Typically, the linear slides are located on the left and right sides of the module from the perspective of a person facing the front of an installed module. This left and right reference will be used throughout this application.) In FIG. 1A, module 202 is in an interior position 108; in FIG. 1B, module 202 is in a partially-extracted exterior position 110A; and in FIG. 1C, module 202 is in a fully-extracted exterior position 110B. It should be appreciated that only the left linear slide is illustrated in the FIGS. 1A-1C; a similar right linear slide on the opposing side of module 102 is hidden from view.
Each linear slide traditionally includes a stationary slide rail secured directly or indirectly to system rack 100, and at least one movable slide rail one of which is secured to a side of module 102. To gain access to module 102, a user slides the module out of the system rack; that is, the user repositions the module from an interior position 108 in system rack 100 to a desired exterior position 10 at least partially outside the rack. Typically, to facilitate ease of access, modules 102 are not restrained in the interior position and are free-floating on the linear slides. As such, a user need only apply a minimal force to reposition module 202 on carrier rail system 104.
Typically, system rack 100 is provided with wheels to facilitate the repositioning of the rack in the same or another data center. During transport, a module 102 mounted on conventional carrier rail system 104 may inadvertently slide to a position outside of the rack. Depending on the component weight, the speed at which the module slides out of the rack, and the elevation of the module in the rack, the rack may tip over, injuring people and damaging equipment. To avoid this, some conventional system racks are provided with a anti-tilt bracket 106, and are accompanied with instructions to install heavy, rail-based modules in lower positions in the system rack. Such precautions, however, cannot always be followed, and fail to protect the system rack and its components under many circumstances.